There are two classifications of cells in the human body, namely, germ cells that are used to make sperm and eggs, and somatic cells making up every other cell in the body including lung cells.  The lung epithelium is composed of a variety of cellular lineages residing in anatomically specific niches found in the trachea, the conducting airways, and the alveoli.  Due to technological advances in genome-wide transcriptional profiling and single-cell sequencing studies have revealed a more complex population of lung epithelial cells.  Now, a study from researchers at Boston University School of Medicine identifies a new lung cell type implicated in the body’s innate immune defense against the bacteria Streptococcus pneumoniae, one of the leading causes of pneumonia worldwide.  The team states their findings may lead to new, non-traditional approaches in the fight against pneumonia and chronic lung diseases. The opensource study is published in the Journal of Clinical Investigation.

Previous studies show it was hypothesized the MIWI2 gene was only expressed in male germ cells as part of a family of genes ensuring the proper development of sperm. The current study shows the same gene is expressed in somatic cells in the body and marks a distinct population of previously unknown multi-ciliated cells lining the upper airways of the lung.

The current study identifies a subpopulation of multiple ciliated airway epithelial cells expressing MIWI2. Results identify the number of cells expressing MIWI2, and the increase in the amount of MIWI2 these cells express during lung infection. Data findings via RNA sequencing demonstrate MIWI2-positive cells have a significantly different transcriptome compared with neighboring multi-ciliated cells not expressing MIWI2.

The lab states their study revealed a functional role for MIWI2 in the homeostatic balance of ciliated and secretory cells in the conducting airways, and in shaping innate immune responses. They go on to add these results reveal multiple ciliated cells previously thought to be homogenous, can now be reclassified into MIWI2-positive and MIWI2-negative subsets.

The team surmises their data identifies a previously unknown subset of airway multi-ciliated cells delineated by MIWI2 expression.  For the future, the researchers state the new cell type may also lead to a better understanding of the mechanisms behind diseases such as COPD and asthma.

Source: Boston University School of Medicine

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